Di- or poly-vinyl functional polymeric compounds, of about 400 to about 10,000 MW, hereinafter called macromers, are known for a long time and are widely used to make UV-curable coatings, films or crosslinked polymeric articles. Typically these compounds are prepared from low molecular weight polyester- or polyether-diols by esterification with acrylic or methacrylic acid, or maleic anhydride; alternatively, they can be more easily prepared by first reacting those polyester- or polyether diols with 2 equivalents of a diisocyanate followed by endcapping with, for instance, 2-hydroxyethyl-methacrylate; such poly-urethane-macromers are described, for instance in U.S. Pat. No. 3,509,234 and U.S. Pat. No. 4,192,827.
An even simpler route to essentially similar urethane-macromers is via the reaction of poly-ester- or poly-ether diols with isocyanate-substituted vinyl monomers, typically a methacrylate such as 2-isocyanatoethyl methacrylate (IEM); relevant patents describing such macromers are U.S. Pat. No. 4,233,425 and U.S. Pat. No. 4,320,221.
The macromer approach has also been applied to polysiloxane (PDMS) dialkanols and PDMS-dialkanol-bis methacrylates are even commercially available. Both urethane based macromer types have also been described, for instance in U.S. Pat. No. 4,136,250, U.S. Pat. No. 4,130,708 and U.S. Pat. No. 4,486,577.
In all instances the linking group between the PDMS-chain and the easily polymerizable vinyl group contains an ester linkage, contribute, either by the hydroxyalkyl- or aminoalkyl methacrylate used in the capping reaction, or by 2-isocyanatoethyl methacrylate. However, this ester linkage constitutes a weakness, if great hydrophilic stability is a requirement, as for example in a PDMS-containing hydrogel.
U.S. Pat. No. 4,837,289 discloses PDMS-tetraalkanols capped wit m-isopropenyl-.alpha.,.alpha.-dimethyl-benzylisocyanate (TMI), thus providing an ester free linkage group.
TMI is a commercially available compound (American Cyanamid) and has been used in a variety of applications, for instance: in the preparation of vinyl-diols (Polym. Mater. Sci. Eng., 57, 565, (1987); in the preparation of macromer for adhesives, by reaction with polyols, for instances poly-tetramethylene ether glycol (Fr. Demande FR 2579611 A1, 1986); in high-solids coatings after reaction of a polyester polyol, as described in U.S. Pat. No. 4,609,706; the reaction of TMI with amines is also disclosed in Poly. Mater., Sci. Eng., 53, 534, (1985).
No reaction products of aminoalkyl-substituted polysiloxanes and m-isopropenyl-.alpha.,.alpha.-dimethylbenzylisocyanate have been described, although the reaction of products of aminoalkyl-substituted PDMS and 2-isocyanto-ethyl methacrylate are described in U.S. Pat. Nos. 4,563,539 and 4,605,712.
It has now been discovered that by reaction of poly-(aminoalkyl)polysiloxane with m-isopropenyl-.alpha.,.alpha.-dimethylbenzyl isocyanate, or any similar styrenic isocyanate, a PDMS-macromer can readily be prepared, which results in superior properties when incorporated into rigid, oxygen permeable polymers or into hydrogels.
It is an object of this invention to provide an easily polymerizable, hydrolytically stable and rigidity imparting urea-polysiloxane macromer.
It is a further object of this invention to make improved rigid, oxygen permeable contact lenses and oxygen permeable hydrogels by copolymerization of said urea-polysiloxane macromer with vinyl monomers.